| Message ID | 1586849715-23490-1-git-send-email-magnus.karlsson@intel.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] xsk: add missing check on user supplied headroom size | expand |
On 4/14/20 9:35 AM, Magnus Karlsson wrote: > Add a check that the headroom cannot be larger than the available > space in the chunk. In the current code, a malicious user can set the > headroom to a value larger than the chunk size minus the fixed XDP > headroom. That way packets with a length larger than the supported > size in the umem could get accepted and result in an out-of-bounds > write. > > Fixes: c0c77d8fb787 ("xsk: add user memory registration support sockopt") > Reported-by: Bui Quang Minh <minhquangbui99@gmail.com> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=207225 > Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Applied, thanks everyone!
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c index fa7bb5e..ed7a606 100644 --- a/net/xdp/xdp_umem.c +++ b/net/xdp/xdp_umem.c @@ -343,7 +343,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) u32 chunk_size = mr->chunk_size, headroom = mr->headroom; unsigned int chunks, chunks_per_page; u64 addr = mr->addr, size = mr->len; - int size_chk, err; + int err; if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { /* Strictly speaking we could support this, if: @@ -382,8 +382,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) return -EINVAL; } - size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM; - if (size_chk < 0) + if (headroom >= chunk_size - XDP_PACKET_HEADROOM) return -EINVAL; umem->address = (unsigned long)addr;
Add a check that the headroom cannot be larger than the available space in the chunk. In the current code, a malicious user can set the headroom to a value larger than the chunk size minus the fixed XDP headroom. That way packets with a length larger than the supported size in the umem could get accepted and result in an out-of-bounds write. Fixes: c0c77d8fb787 ("xsk: add user memory registration support sockopt") Reported-by: Bui Quang Minh <minhquangbui99@gmail.com> Link: https://bugzilla.kernel.org/show_bug.cgi?id=207225 Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> --- net/xdp/xdp_umem.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)